Combine any OLAS transmitter with the free OLAS mobile app to create a portable overboard alarm system. For added benefits, use the OLAS Core, a USB-powered tracker and alarm hub that can be easily transferred between vessels. Worn by the skipper and crew, OLAS transmitters wirelessly connect to the OLAS receiver (mobile phone or Core). The receiver alerts you if a transmitter moves out of range or in a man overboard situation. Additionally, the OLAS Extender can be used with the OLAS Core to extend the recommended vessel coverage by 25 ft in a linear direction from the Core, multiple Extenders can be used.